This specification relates to imaging systems such as cameras including infrared cameras and in particular to a system and method for analog to digital conversion with extended dynamic range and enhanced image display of image data from infrared (IR) focal plane arrays, and in particular for thermal imaging.
Infrared imaging sensors have long been expensive and difficult to produce, thus limiting the employment of high performance, long wave imaging (thermal imaging) to high value instruments, such as aerospace, military, or large scale commercial applications. For many of these applications, the systems are designed for temperature resolution and radiometric accuracy. High performance, low cost uncooled infrared (IR) imaging devices, such as bolometer focal plane arrays (FPA's), can be used for mass produced, consumer oriented IR cameras. Low cost, high volume IR imaging devices have different design challenges and constraints than high value systems, and the visual image may be a goal of the system design.
An IR focal plane array (FPA) for an IR camera is typically a two-dimensional array of photodetectors interfaced and integrated with a Readout Integrated Circuit (ROIC or “readout”) to form a sensor chip, the heart of an IR camera. To reduce cost and simplify the camera design, as much of the signal processing electronics as possible is integrated into the readout component of the FPA. Readout design options are limited by power consumption, space and microfabrication design rules.